Everything You Need to Know about Narcissists, Psychopaths, and Abuse - click on this link: http://www.narcissistic-abuse.com/faq1.html
The narcissist abuses his intimate partners, significant others, and nearest and dearest because it helps him to regulate his excruciating abandonment anxiety in 4 ways:
(1) Devlauing others restores his sense of superiority and grandiosity;
(2) He preempts his own abandonment by precipitating it and, thus, controlling the situation;
(3) His abusive conduct helps him to learn more about his "loved" ones by observing their reactions and this added information alleviates his anxiety;
(4) Abuse works: it leads to the modification of the victims' behavior and to submissiveness.
There are 5 effective coping styles:
(2) Counterdependent/conflictive stance;
(5) Displacement (redirecting the abuse at third parties) which is a form of cultish shared psychosis.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 3 DVDs with 16 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)